It is proposed to hold a conference on control mechanisms in the fetal and neonatal pulmonary circulation in Colorado from September 10th to 13th, 1998. This is the ninth in a series of conferences on the Pulmonary Circulation. The proceedings to prior meetings have appeared in Chest (1985), the American Review of Respiratory Disease (1987 and 1989), and as books published by Futura Publishing Co., and Plenum Press. The conference will have a total of 25 speakers (all but 1 have already agreed to attend) and 8 chairs. An additional 50 to 60 participants are anticipated, who will be encouraged to bring posters. Equal time will be given to presentations and discussion. Each session will be summarized by the chair, who will also lead the poster discussion on the same topic. The objectives of this conference are: 1) To determine the cellular and molecular factors controlling vasculogenesis in the lung. 2) To examine the interaction of the genetic and molecular factors responsible for vascular cell differentiation and function. 3) To elucidate the role of extracellular matrix proteins in stimulation of vascular cell proliferation and activity in the lung. 4) To integrate our knowledge on the mechanisms controlling tone in the transitional circulation. The information developed at this conference will be disseminated as a book, rather than in a journal, because the presentations are in many cases the summation of research experience, rather than the results of circumscribed experiments which could be published as original data. This application requests funding for printing the program, mailing costs, partial reimbursement of the airfares of domestic speakers, and the rental of poster boards. This is the ninth Pulmonary Circulation conference at the same venue, so the logistics of organizing the meeting will be relatively easy.